Hi Guys and Girls,
After many years of looking I’ve taken the plunge and joined your ranks so its a hello from me. There is now a pretty shiny 1948 flying Squirrel sat in the garage next to my other bikes (Ducati ST4S, Suzuki RG500, Cyclemaster and Honda CRM250). I’m (mostly) a two stroke fan and love classic trackdays so its certainly not going to be parked up as a museum piece. I’m pretty handy mechanically but as a complete Scott newbie I hope you will extend more than the usual patience with me. I was originally going to park it in the basement and attend to the various faults over the winter. However, while I’ve been waiting for my forum access to be approved I’ve started to to tinker and wade my way through Technicalities and as much info as I can get hold of. I’ve already been in touch with Roger Moss who worked his magic on the engine a few years back but there is still much to learn…..
The biggest problem I face at the moment is that I don’t know what is normal and what is Scott ‘character’. Thus, I’m hoping to make it to the next East Midlands meet on the bike so I can consult wiser heads. I’ve managed to take it for a few runs but still very much coming to terms with it. It doesn’t like running at low rpm but certainly picks its skirts up when the throttle is cracked open and would certainly leave my Dads Speedtwin in its wake. However, I’m pretty sure that you should be able to notice at least some slight change in retardation rate when yanking the front brake on as hard as possible! That has to be first on the ‘to do’ list as the rear brake is good but someone appears to have fitted it to the wrong side 😆 Second on the list is the air forks which are not keen on holding onto either air or oil Even I am pretty certain its not normal to have to pump them up before every trip. Third, the gearbox doesn’t like changing down (perhaps this is simple lack of technique) and its clearly over-oiling . I’ve have managed to tick off a carb and dynamo rebuild and its charging again so some small progress has been made.
I sense I am still on the first part of a very steep learning curve….
Hi Keith!!!!!!!!! 😀 😀 I too have a later Scott brake (IE retardation device) On my MPG Scott racer. I am investing in a good pair of hobnail boots to augment them! 😐 😐 😐 Pop over on the bike to see Roger Moss at South Croxton. All will be revealed with humour and a cup of Tea! Make an appointment mate. He is ALWAYS busy! Regards Ted!!!!! 😀 😀
Welcome to a great little Club, largely composed of eccentrics. You have to be leaning at least a bit that way to ride a Scott.
Regarding the post-war Shipley front brake – you are just the latest in a long line of owners to bemoan its lack of performance, at the same time puzzling as to why such a decent looking, twin brake, should be so bad. Your timing however is spot-on as there is recent correspondence about it in the October issue of Yowl starting on page 422. My opinion is that the root problem lies in the mudguard mounted compensator which halves the force applied to the backplate levers, with a spongy stay system on the mudguard itself coming a close second.
Have a read, and also look in Technicalities 8.4.19 for Jim Ogden’s article from 1981.
I look forward to meeting you on Sunday November 11th at “The Vale of Belvoir” pub/hotel. Our Membership Secretary has already given me your details. I assume that you will have received a copy of Yowl by now, and my details are in there if you need to contact me direct.
Thanks for the welcome! I’m still waiting on my Yowl but hopefully I’ll get the October edition shortly. I’m certainly looking forward to making the November East Mids meeting especially if the weather is not too unkind so I can take the Scott. One of my aims is to persuade someone to take it for a spin for an opinion on the low speed running and gearbox!
I guessed that Scott owners would be a tad eccentric to match the bike. I’m sure I’ll fit in fine 😀
My front brake appears stock but the original compensator etc has been replaced by a ‘twin pull’ front brake lever. I did try increasing the leverage at the lever (I had read that particular Technicalities article) but all that did was make the brake really spongy. However, I stripped the brake out again yesterday and my linings are back to being black and greasy. I cleaned them up a couple of weeks back but they are clearly deeply contaminated. Thus, I have just sent them off to Saftek for a re-line to see if that helps. When I get them back I’ll mount them in the brake plates and try turning them down to the exact hub diameter in the lathe. I’ve not tried that trick before that before but it sounds like a worthwhile exercise to maximise friction.
Hopefully managed to add a picture of the new pride and joy…..
All is revealed ! The ex-Shelley machine…..
Ah, clearly the bike is known! I feel a certain nervousness about if that is good or bad 😆
Its still looking good despite the many years since his restoration though has certainly picked up some ‘patina’ over the years. Its a joy to work on as nothing is mangled and botched which is a marked contrast to all the other British bikes I’ve worked on.
Hi, Geoff Ingram from the wide brown land of Australia. It is nearly summer and the bloody heater is on.
I have had a 1949 Scott for about 5 years now and have to say the front brake is about the best drum brake I have ever used. It is easily a match for a good mates Velocette Thruxton twin leading shoe
When I first bought the bike the brake was not very good but a good clean and grease of the box transformed the brake.
I learnt in 1980 as the owner of a 125 KTM enduro bike that drums like to be clean and correctly lubricated to work properly.
The performance of the twin front brake on the Scott has nothing to do with how how the box is mounted to the front muguard.
The forces of the inner cables are taken by the outer cables, the compressive forces from the handlebar lever go through the outer cable from the handlebar lever to the box, through the box to the outer cables from the box to the brake plates. The brake may well work a little better if the box was just floating around as the cables could then be in their “natural” position. Although the rattle and scatched paint could be a pain.
If anone tries this could you let me know the results. Braking results not rattle and scratched paint results.
I have been having a wonderful time with my Scott of late.
Friday I found a cracked left crank.
Saturday I found a cracked right crankcase.
I am hoping Roger Moss has some cranks to sell.
If anyone has advice about welding crankcases I will listen.
At the moment I am considering using an aluminium brazing rod called Ultrabond. Its melting pont is only 380 degress C and strength greater than aluminium.
Strength of bond can be good depending on stuff. Mainly cleanliness.
I have had very mixed results from attempts at welding Scott crankcases over the years, from both my amateur attempts, and from top-notch professional alloy welders, and I’ve come to the conclusion that the factory changed alloy casting suppliers from time to time, and that the quality of the metal varied accordingly. Whilst the straight-back crankcases of 1927/8 are usually quite good, there are some around that have a markedly darker colour to them, and they are almost impossible to get a good polish on, and tricky to weld. The late 1928 and 1929 RZ and RY crankcases are VERY brittle, prone to cracking, and difficult to weld. Once they have cracks around the main bearing cup housings they are usually beyond redemption. Things then seem to have gradually improved through the 1930’s, but there were some bad crankcases immediately after the war, when there was a huge glut of scrap aluminium around from the scrapping of thousands of aircraft. Instead of ‘virgin’ metal, it would be an unpredictable brew of duralumin, aluminium, and maybe some magnesium or zinc thrown in for good measure.
When metal is relatively porous it becomes oil-saturated, and that of course prevents good welds being achieved. In conclusion, it is all really a matter of ‘pot luck’, melting pot luck !
I have welded and attempted to weld many Scott crankcases, perhaps ~15 in the last couple of years. Some I’ve welded huge amounts of damage that I thought were scrap and they welded fine in half an hour. Others with what looked like minor damage have been scrapped after hours of trying to rescue them. I cannot identify a true pattern of which are better than others. Some early ones are fine, and some made only months apart are impossible. The two biggest issues are oil impregnation deep into the (porous) casting, and the other is micro cracking, I hypothesise from long term fatigue, that propogates with the heat and stress of welding. These become an impossible task of chasing cracks around the crankcase unti you give up. The problem is not the weld itself but the crankcase material around it that needs no excuse to start a crack. It depends where the damage is and how much it is. Can you post up a photo?
Thanks to Geoff Ingram for correcting some woolly thinking on my part! On reflection, I agree with his statement that the Scott compensator does not need to be mounted on the mudguard to function – the compressive forces in the upper and lower cable outers balance each other out so there is no net vertical component. There will be a small horizontal force due to the compensator being fixed to the mudguard, causing only a slight deflection. Mea culpa!
The same does not apply to the Vincent-style balance arm conversion which needs a mudguard mounted pivot, and very definitely does exert a large downward deflecting force. Hence the need to beef up the mudguard and its stays. This adds complication and weight but it does double the leverage making the brake twice as powerful. Of course the movement of the handlebar lever is also doubled – you don’t get anything for nothing.
I confess to being very surprised by Geoff’s assertion about “the best drum brake I have ever used” and apparently just needing a good clean and greasing. The comments received and read about over the years, and my own experience, all point in the opposite direction. Possibly he has a vice-like grip in his right hand – the legendary “six inch steel fingers” that Vincent owners used to say were necessary to stop their beasts. The Scott cast iron brake drums are very well supported by the hub and stiff enough to respond to heavy input loads without serious distortion, which may help to explain the success of the Vincent-style conversion. There is no escaping the very small drum diameter. Six inches is just not enough.
There is no escaping the fact either that sharing the input force between twin drums halves the force, also true of twin cables up to the handlebar. Actually, the compensator could have a slight edge here as the lower cables do not emerge vertically but a bit splayed, caused by the geometry of the internal balancing pulley. This effect increases the power by perhaps 10% ? Making sure that adjustments concentrate on the backplate levers will keep the pulley as low as possible. I have speculated about a modified compensator mechanism to multiply the force but it’s a difficult design exercise and none of my ideas look workable.
I forgot to mention that a longer handlebar lever, and/or a reduced lever pivot offset, have the potential to multiply the force going into the compensator.
Comments about increased lever movement apply but this may be the simplest approach to a longstanding problem.
…or simply dispense with the compensator and fit a Birmingham type lever which connects the two cables directly to the brakes.
Unfortunately, Lewis, the little compensator at the handlebar divides the force in the same way as the box on the mudguard.
The twin cable setup is admittedly simple and direct and is widely used on twin brake bikes, including Birmingham Scotts. Why does it work for them? I think because the brake drum diameter is bigger – to my limited knowledge, 7 inches would be a minimum. Quite a proportion of them have two leading shoes as well.